1. Field of the Invention
The present invention relates to a micromechanical component, which is composed of multiple layers, for example electrically conductive and non-conductive layers or areas, or layers or areas made of metallic and non-metallic materials, and a method for its production.
2. Background Information
In a component used as a microvalve and described in German Patent Application No. 39 19 876, individual layers are processed by micromechanical production methods in the construction of the microvalve. For example, the surface of a silicon wafer is patterned by photolithography and predetermined areas partially removed in a subsequent etching step, thus forming the mechanical elements by processing these layers in a three-dimensional pattern.
Conventional production methods include UV gravure lithography for patterning the non-conductive areas and multilayer electroplating for producing metallic, conductive areas. In this case, a conductive start layer for later electrodeposition with the application of external current in the proper areas is also needed on non-conductive carrier layers.
Conductive metal layers applied as carrier layers to the entire surface of non-conductive substrates are known as metallic start platings. These start layers can be applied by resist-coating (spraying, dipping, spinning, etc.) or with the aid of various wet-chemical methods or PVD (physical vapor deposition) methods (vaporization, sputtering, etc.). They either have an intrinsic electrical conductivity that is sufficient for electroplating with the application of external current or are used as the nucleation layer for deposition of a metal layer without the application of external current, which, in turn, serves as the start layer for subsequent multilayer electroplating with the application of external current.
Wet-chemical methods (DMS-E methods) for patterning surfaces are also known from p.c. board technology discribed in European Patent Application No. 0 206 133), for example, in order to make the holes drilled into the p.c. board conductive. In this case, a start layer is patterned or applied selectively to the non-conductive areas of the p.c. board surface, thus making the entire surface electrically conductive. However, these processing methods are incompatible with the processes of UV gravure lithography and multilayer electroplating because they lack the necessary precision.
Methods which allow two metal layers on an intermediate layer to be separated are also known. To do this, the intermediate layer is selectively removed from the remaining materials in the form of a sacrificial layer by etching or stripping. This method leaves gaps measuring several .mu.m thick between the layers to be separated, which is disadvantageous especially when tight-fitting surfaces need to be produced which will also be used as sealing surfaces.